156 lines
4.4 KiB
ReStructuredText
156 lines
4.4 KiB
ReStructuredText
.. SPDX-License-Identifier: GFDL-1.1-no-invariants-or-later
|
|
.. c:namespace:: V4L
|
|
|
|
.. _VIDIOC_DBG_G_CHIP_INFO:
|
|
|
|
****************************
|
|
ioctl VIDIOC_DBG_G_CHIP_INFO
|
|
****************************
|
|
|
|
Name
|
|
====
|
|
|
|
VIDIOC_DBG_G_CHIP_INFO - Identify the chips on a TV card
|
|
|
|
Synopsis
|
|
========
|
|
|
|
.. c:macro:: VIDIOC_DBG_G_CHIP_INFO
|
|
|
|
``int ioctl(int fd, VIDIOC_DBG_G_CHIP_INFO, struct v4l2_dbg_chip_info *argp)``
|
|
|
|
Arguments
|
|
=========
|
|
|
|
``fd``
|
|
File descriptor returned by :c:func:`open()`.
|
|
|
|
``argp``
|
|
Pointer to struct :c:type:`v4l2_dbg_chip_info`.
|
|
|
|
Description
|
|
===========
|
|
|
|
.. note::
|
|
|
|
This is an :ref:`experimental` interface and may
|
|
change in the future.
|
|
|
|
For driver debugging purposes this ioctl allows test applications to
|
|
query the driver about the chips present on the TV card. Regular
|
|
applications must not use it. When you found a chip specific bug, please
|
|
contact the linux-media mailing list
|
|
(`https://linuxtv.org/lists.php <https://linuxtv.org/lists.php>`__)
|
|
so it can be fixed.
|
|
|
|
Additionally the Linux kernel must be compiled with the
|
|
``CONFIG_VIDEO_ADV_DEBUG`` option to enable this ioctl.
|
|
|
|
To query the driver applications must initialize the ``match.type`` and
|
|
``match.addr`` or ``match.name`` fields of a struct
|
|
:c:type:`v4l2_dbg_chip_info` and call
|
|
:ref:`VIDIOC_DBG_G_CHIP_INFO` with a pointer to this structure. On success
|
|
the driver stores information about the selected chip in the ``name``
|
|
and ``flags`` fields.
|
|
|
|
When ``match.type`` is ``V4L2_CHIP_MATCH_BRIDGE``, ``match.addr``
|
|
selects the nth bridge 'chip' on the TV card. You can enumerate all
|
|
chips by starting at zero and incrementing ``match.addr`` by one until
|
|
:ref:`VIDIOC_DBG_G_CHIP_INFO` fails with an ``EINVAL`` error code. The number
|
|
zero always selects the bridge chip itself, e. g. the chip connected to
|
|
the PCI or USB bus. Non-zero numbers identify specific parts of the
|
|
bridge chip such as an AC97 register block.
|
|
|
|
When ``match.type`` is ``V4L2_CHIP_MATCH_SUBDEV``, ``match.addr``
|
|
selects the nth sub-device. This allows you to enumerate over all
|
|
sub-devices.
|
|
|
|
On success, the ``name`` field will contain a chip name and the
|
|
``flags`` field will contain ``V4L2_CHIP_FL_READABLE`` if the driver
|
|
supports reading registers from the device or ``V4L2_CHIP_FL_WRITABLE``
|
|
if the driver supports writing registers to the device.
|
|
|
|
We recommended the v4l2-dbg utility over calling this ioctl directly. It
|
|
is available from the LinuxTV v4l-dvb repository; see
|
|
`https://linuxtv.org/repo/ <https://linuxtv.org/repo/>`__ for access
|
|
instructions.
|
|
|
|
.. tabularcolumns:: |p{3.5cm}|p{3.5cm}|p{3.5cm}|p{6.6cm}|
|
|
|
|
.. _name-v4l2-dbg-match:
|
|
|
|
.. flat-table:: struct v4l2_dbg_match
|
|
:header-rows: 0
|
|
:stub-columns: 0
|
|
:widths: 1 1 2
|
|
|
|
* - __u32
|
|
- ``type``
|
|
- See :ref:`name-chip-match-types` for a list of possible types.
|
|
* - union {
|
|
- (anonymous)
|
|
* - __u32
|
|
- ``addr``
|
|
- Match a chip by this number, interpreted according to the ``type``
|
|
field.
|
|
* - char
|
|
- ``name[32]``
|
|
- Match a chip by this name, interpreted according to the ``type``
|
|
field. Currently unused.
|
|
* - }
|
|
-
|
|
|
|
|
|
.. tabularcolumns:: |p{4.4cm}|p{4.4cm}|p{8.5cm}|
|
|
|
|
.. c:type:: v4l2_dbg_chip_info
|
|
|
|
.. flat-table:: struct v4l2_dbg_chip_info
|
|
:header-rows: 0
|
|
:stub-columns: 0
|
|
:widths: 1 1 2
|
|
|
|
* - struct v4l2_dbg_match
|
|
- ``match``
|
|
- How to match the chip, see :ref:`name-v4l2-dbg-match`.
|
|
* - char
|
|
- ``name[32]``
|
|
- The name of the chip.
|
|
* - __u32
|
|
- ``flags``
|
|
- Set by the driver. If ``V4L2_CHIP_FL_READABLE`` is set, then the
|
|
driver supports reading registers from the device. If
|
|
``V4L2_CHIP_FL_WRITABLE`` is set, then it supports writing
|
|
registers.
|
|
* - __u32
|
|
- ``reserved[8]``
|
|
- Reserved fields, both application and driver must set these to 0.
|
|
|
|
|
|
.. tabularcolumns:: |p{6.6cm}|p{2.2cm}|p{8.5cm}|
|
|
|
|
.. _name-chip-match-types:
|
|
|
|
.. flat-table:: Chip Match Types
|
|
:header-rows: 0
|
|
:stub-columns: 0
|
|
:widths: 3 1 4
|
|
|
|
* - ``V4L2_CHIP_MATCH_BRIDGE``
|
|
- 0
|
|
- Match the nth chip on the card, zero for the bridge chip. Does not
|
|
match sub-devices.
|
|
* - ``V4L2_CHIP_MATCH_SUBDEV``
|
|
- 4
|
|
- Match the nth sub-device.
|
|
|
|
Return Value
|
|
============
|
|
|
|
On success 0 is returned, on error -1 and the ``errno`` variable is set
|
|
appropriately. The generic error codes are described at the
|
|
:ref:`Generic Error Codes <gen-errors>` chapter.
|
|
|
|
EINVAL
|
|
The ``match_type`` is invalid or no device could be matched.
|